For some time, V-Bucket Conveyor and Pivoted Bucket Conveyor have been known as equipment for continuously conveying loose grain from horizontal to vertical direction. With the V-Bucket Conveyor, the opening of the bucket is always perpendicular to the direction of conveyance and the bucket travels through a trough in the horizontal direction to scoop up the loose grain. Accordingly, friction between the bucket and trough is high which causes high dynamic loss. Also, the loose grain is easily damaged and split open. With the Pivoted Bucket Conveyor, the bucket is attached to the chain by a pin, therefore the opening of the bucket faces upwards no matter where the bucket is located. Accordingly, a mechanism is needed to flip the bucket over at the unloading point and, because the flip roller, cam and bucket are subjected to considerable shock, structure and materials must be designed against shock. Moreover, conveying speed is limited because of the flip operation. And, if the loose grain is not loaded in the center of the bucket, the bucket will tilt and spill the grain. Therefore, a device is needed to control the relative positions of the loading port and the bucket.
A bucket conveyor having a rectangular parallelepiped bucket with a 45.degree. angle opening attached to a chain has been proposed for this purpose (Japanese Utility Model Appln. Laid-Open No.36312/1989). When using this conveyor to transport loose grain, grain gathered under the lower part of the conveyor is scooped up by the bucket on it's return trip. On the forwarding trip, the opening faces diagonally upward both in horizontal conveyance and vertical conveyance, and loose grain is filled up to the diagonal line of the square bucket, thus 1/2 way full. On the returning trip, the opening faces diagonally downward, therefore the bucket dumps the loose grain.
Other type of bucket conveyor having cylindrical or spherical buckets with a similar 45.degree. angle opening, which are attached into a continuous gapless train has been proposed (Japanese Pat. Appln. Laid-Open No. 072519/1994). When using this conveyor to transport loose grain, grain is poured from above the bucket and slid along the rear end of the preceding bucket to fall into the opening. Therefore, in addition to the same filling and dumping capacities of the aforementioned proposal, this conveyor has the advantage that loose grain can be loaded continuously.
With the conveyor described in Japanese Utility Model Appln. Laid-Open No.36312, the loose grain gathered under the conveyor is not completely scooped up. Moreover, loose grain is subjected to shock in the scooping process which damages the grain or splits it open.
With the conveyor described in Japanese Pat. Appln. Laid-Open No.072519, the bucket is only filled 1/2 full so as not to overflow. Accordingly, it is necessary to control speed of loading the bucket in line with the conveyance speed of the conveyor. Of course, when power is lost, the conveyor stops because the control device stops working. However despite this, the loading port remains open and loose grain is loaded continuously until overflowing. In this state, when the conveyor is restarted, loose grain is spilled when the bucket angle changes. The spilt grain piles up on the bottom of the conveyor which makes it harder to drive the conveyor. Furthermore, it is very troublesome to clean up spilled grain because there is little space between the conveyor case and bucket.